Stingless bees have been recognized as essential plant pollinators and producers of various natural products in neotropical areas. Research into the potential risks of pesticides they may be exposed to in agricultural fields, however, remains meagre. Especially the toxicity of pesticide mixtures likely to occur under real-world conditions and that are likely to exert synergetic effects has been poorly studied. The aim of the present study was therefore to evaluate the single and mixture acute contact and oral toxicity of commercial products containing the insecticide abamectin and the fungicide difenoconazole in laboratory bioassays with the Brazilian native stingless bee Melipona scutellaris. In addition, a comparison of the insecticide sensitivity of stingless bees relative to the honeybee Apis mellifera was made based on previously published toxicity data. Except for oral exposure to abamectin, M. scutellaris appeared to be more sensitive that A. mellifera in the single compound toxicity tests. A difenoconazole concentration at the NOEC (no observed effect concentration) level indicated a synergetic toxic interaction with abamectin. A sensitivity comparison based on published toxicity data for A. mellifera and stingless bees indicated several insecticidal modes of action having a high relative sensitivity to stingless bees that need especial consideration in future studies. The research findings highlight the need for testing native bee species and environmentally relevant pesticide mixtures in risk assessments to avoid underestimation of potential risks to bee populations and the subsequent loss of pollination ecosystem services.
Um estudo sobre os impactos ambientais causados por atividades agrícolas e industriais, ao longo da bacia do rio Mogi Guaçu, foi realizado neste trabalho. A concentração de alguns metais (Fe, Cd, Cu, Cr, Zn, Ni, Pb e Mn) foi determinada em quinze estações de coleta de sedimentos e em dois períodos diferentes: chuvoso (Março/2001) e seco (Junho/2001). Os métodos de reconhecimento de padrões PCA e HCA foram utilizados para agrupar as amostras coletadas em São Paulo e em Minas Gerais e obter informações relevantes sobre as possíveis fontes de contaminação do rio Mogi Guaçu de acordo com o período de coleta das amostras. As análises quimiométricas realizadas, utilizando as amostras coletas em Março/2001 e em Junho/2001, indicaram que somente a concentração de Cd, Cu, Cr e Pb discrimina as amostras coletadas em São Paulo das amostras coletadas em Minas Gerais. A influência do período de coleta também foi analisada e os resultados obtidos indicaram que a concentração de quatro metais (Cd, Cr, Zn e Mn) foi importante para discriminar as amostras coletadas em Março/2001 das amostras coletadas em Junho/2001. De forma geral, a concentração dos metais estudados se apresenta em altos níveis em todas as estações de coleta e este fato caracteriza um ambiente com alto grau de contaminação causada, principalmente, por atividades antropogênicas. A study on the environmental impacts caused by agricultural and industrial activities along the Mogi Guaçu river basin was carried out. Concentrations of some metals (Fe, Cd, Cu, Cr, Zn, Ni, Pb and Mn) were determined for fifteen collection stations in two different seasons: rainy (March/2001) and dry (June/2001). Pattern recognition methods (Principal Component Analysis and Hierarchical Cluster Analysis) were used to group samples collected in São Paulo and Minas Gerais and obtain relevant information on possible polluting sources of the Mogi Guaçu river according to the collection season of the samples. A chemometric analyses performed using samples collected in March/2001 and June/2001 indicated that only the concentrations of Cd, Cu, Cr and Pb discriminate samples collected in São Paulo from those collected in Minas Gerais. The influence of the collection season was also analysed and the results indicated that four metals (Cd, Cr, Zn and Mn) were important to discriminate samples collected in March/2001 (rainy season) from those collected in June/2001 (dry season). We verified that the concentrations of the metals studied are at high levels in all collection stations and this fact characterizes an environment with a high degree of contamination caused mainly by anthropogenic activities.
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